A method for selectively hydrodealkylating aromatics coupled with xylene isomerization

Abstract

The application discloses a method for selectively hydrogen-dealkylating aromatics and coupling xylene isomerization. + The method comprises the following steps: contacting aromatics, PX-lean C8 aromatics and a catalyst to perform selective hydrogen-dealkylation and xylene isomerization; wherein the catalyst comprises catalyst A, catalyst B and catalyst C, catalyst A is arranged upstream of catalyst B, and catalyst C is arranged downstream of catalyst B; wherein the catalyst A is a composite modified alumina; the catalyst B and the catalyst C are independently selected from group VIII metal modified molecular sieves. + The method provided by the application can concentrate a reaction unit to selectively hydrogen-dealkylate C8 10 C2 + The method can realize xylene isomerization in the PX-lean C8 aromatics while selectively hydrogen-dealkylating the side chains, and can cooperate with liquid phase transalkylation technology, so that an isomerization unit in an existing process is omitted, and device energy consumption, material consumption and investment are greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of aromatic catalytic conversion, and more specifically to a method for selective hydrogenation and dealkylation of aromatics while simultaneously coupling xylene isomerization. Background Technology

[0002] Catalytic reforming refers to the rearrangement of hydrocarbon molecules into new molecular structures, which can convert light gasoline fractions (or naphtha) obtained from crude oil distillation into high-octane gasoline rich in aromatics (reformed gasoline), and produce liquefied petroleum gas and hydrogen as byproducts. Reformed gasoline can be used directly as a blending component of gasoline, or it can be separated to produce aromatic products such as benzene, toluene, and paraxylene.

[0003] Based on the number of carbon atoms in aromatic hydrocarbons, the main aromatic products of catalytic reforming are benzene, toluene, C8 aromatics, and C9 aromatics. + Heavy aromatics. A common aromatics production unit is the aromatics complex, whose main products are benzene and para-xylene (PX). The process of an aromatics complex is roughly as follows: the reformate passes through a depentanizer and a reformate separator. The C7 hydrocarbons at the top of the reformate separator... - Aromatics are extracted in the aromatics extraction unit to obtain benzene, toluene, and raffinate. The bottom feed from the reformate separator passes through a xylene tower, where C8 aromatics are separated at the top and C9 aromatics at the bottom. + Aromatics enter the heavy aromatics column. C9 / C hydrocarbons are separated from the top of the heavy aromatics column. 10 Aromatics, along with toluene, then enter the toluene disproportionation and alkyl transfer unit to increase the production of C8 aromatics and benzene. The C8 aromatic stream passes through the PX separation unit (adsorption separation or crystallization separation unit) to separate PX. The remaining PX-depleted C8 aromatics enter the isomerization unit, and the isomerized C8 aromatics product then enters the PX separation unit (Aromatics Technology [M]. Beijing: China Petrochemical Press, 2014). In fact, in addition to benzene, toluene, and trimethylbenzene, a large amount of C2-containing aromatics are also generated in the aromatics produced by catalytic reforming. + Aromatic hydrocarbons with side-chain substituents, such as C8 aromatic hydrocarbons, contain ethylbenzene in addition to xylene. These two isomers cannot be effectively separated by a xylene column. Similarly, C9 / C... 10Besides xylene and tetramethylbenzene, aromatic hydrocarbons also contain isomers such as ethylbenzene, propenylbenzene, and butanylbenzene. Heavy aromatic hydrocarbon towers cannot effectively separate these complex components. Therefore, in an aromatic hydrocarbon complex, the isomerization unit needs to not only perform xylene isomerization but also ethylbenzene conversion to prevent ethylbenzene from accumulating in the aromatic hydrocarbon complex and reducing PX recovery. According to function, there are two typical technologies for isomerization units (Research progress on xylene isomerization catalysts [J]. Chemical Industry and Engineering Progress, 2004, 23(3):244-259.): (1) Deethylation isomerization, that is, while xylene isomerization is achieved, ethylbenzene will be converted into benzene and ethane through hydrogenation deethylation reaction; (2) Ethylbenzene conversion isomerization, that is, while isomerization is achieved, ethylbenzene will be catalytically converted into xylene. Similarly, in addition to achieving methyl transfer reactions between aromatic hydrocarbons, such as the methyl transfer reaction between toluene and toluene to produce benzene and xylene, and the methyl transfer reaction between toluene and trimethylbenzene to produce xylene, the toluene disproportionation and alkyl transfer unit also needs to have selective hydrogenation dealkylation capabilities to remove C2 atoms from isomers such as ethylbenzene, propylbenzene, and butadiene. + Effective removal of side chain substituents (Advances in toluene disproportionation and alkyl transfer technology [J]. Chemical Technology and Economy, 2006, 24(002):13-16.).

[0004] Therefore, in aromatic hydrocarbon complexes, the deethylated xylene isomerization technology requires the hydrogenation removal of the ethyl group from ethylbenzene while simultaneously achieving xylene isomerization; and C9 / C 10 C2 in aromatics + The side chain needs to be hydrogenated and removed in the toluene disproportionation and alkyl transfer unit. A C8... + The method of selective hydrogenation and dealkylation of aromatics coupled with xylene isomerization is of great significance. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a method for the selective hydrogenation and dealkylation of aromatics coupled with xylene isomerization. This method concentrates a single reaction unit on C8... + C8 / C9 / C in aromatics 10 C2 in aromatics + While selectively removing the side chain by hydrogenation, xylene isomerization in PX-poor C8 aromatics can also be achieved. This method can be combined with liquid-phase alkyl transfer technology to eliminate the isomerization unit in the existing process, thereby significantly reducing the energy consumption, material consumption and investment of the equipment.

[0006] This invention provides a method for selective hydrogenation and dealkylation of aromatics coupled with xylene isomerization, including C8... + Aromatic hydrocarbons, PX-depleted C8 aromatic hydrocarbons, and catalysts undergo selective hydrogenation-dealkylation and xylene isomerization reactions.

[0007] The catalyst includes catalyst A, catalyst B, and catalyst C, with catalyst A positioned upstream of catalyst B and catalyst C positioned downstream of catalyst B; catalyst A is a composite modified alumina; catalyst B and catalyst C are each independently selected from group VIII metal modified molecular sieves.

[0008] Furthermore, in catalyst B, the molecular sieve modified with group VIII metals has a particle size distribution of 100–1000 nm; in catalyst C, the molecular sieve modified with group VIII metals has a particle size distribution of 10–50 nm.

[0009] Furthermore, the C8 + Aromatic hydrocarbons are C2-containing hydrocarbons. + C8 of side chain substituents (C2 and above side chain substituents) + Aromatic hydrocarbons (monocyclic aromatic hydrocarbons with eight or more carbon atoms), preferably containing C2. + C8 / C9 / C of single-ring side chain 10 Aromatic hydrocarbons (i.e., C8 / C9 / C4) 10 Aromatic hydrocarbons are selected from C8 aromatic hydrocarbons, C9 aromatic hydrocarbons, and C4 aromatic hydrocarbons. 10 (At least one of the aromatic hydrocarbons). This invention relates to C2-containing hydrocarbons. + C8 of side chain substituents + The source of aromatics is not particularly limited, and may include, but is not limited to, at least one product from processes such as catalytic reforming, hydrocracking of cracked gasoline, and hydrocracking. The C8... + Aromatic hydrocarbons contain C2 + C8 of side chain substituents + The mass content of aromatics is generally above 10%, and can be 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, etc.

[0010] Furthermore, the Xylene content in the PX-depleted C8 aromatic hydrocarbon is above 80% by mass, and the PX content is below 5% by mass.

[0011] Furthermore, the C8 + The mass ratio of aromatic hydrocarbons to PX-depleted C8 aromatic hydrocarbons is (10–90):(90–10).

[0012] Furthermore, the selective hydrogenation-dealkylation reaction is for C8... + C2 in aromatics + Selective hydrogenation removal of ethylbenzene substituents in side chains and PX-depleted C8 aromatics.

[0013] Furthermore, the xylene isomerization reaction is a reaction in which o-xylene and m-xylene in the reaction are isomerized to obtain p-xylene.

[0014] Furthermore, the operating conditions of the reaction include: a reaction temperature of 300–450°C; a reaction pressure of 0.5–5 MPa; and an aromatic feedstock consisting of C8 hydrocarbons. + Based on aromatics and PX-lean C8 aromatics, the ratio of the mass hourly space velocity (MHSV) of the aromatic feedstock on catalyst A to that on catalyst B is 5–50; the ratio of the MHSV of the aromatic feedstock on catalyst A to that on catalyst C is 5–50; and the ratio of the MHSV of the aromatic feedstock on catalyst B to that on catalyst C is 5–50. + Aromatic hydrocarbon mass hourly space velocity (MH) is 2–10 h⁻¹ -1 The mass space velocity of the aromatic feedstock on catalyst C is 2–10 h⁻¹. -1 The molar ratio of hydrogen to aromatic feedstock is 1–10 mol / mol.

[0015] Furthermore, the catalyst A is a composite modified alumina, comprising a modified metal and alumina.

[0016] Further, the modified metal in catalyst A includes at least two metals from Group VIII, Group VIB, and Group VIIB; wherein the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0-8):(0-8):(0-8), preferably, the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0.01-8):(0.01-8):(0-8), preferably, the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0-8):(0.01-8):(0.01-8), preferably, the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0.01-8):(0-8):(0.01-8).

[0017] Furthermore, in catalyst A, the group VIII metal is selected from at least one of Pt, Ni and Co; the group VIB metal is Mo; and the group VIIB transition metal is Re.

[0018] Furthermore, in catalyst A, based on the mass of catalyst A, the mass content of modified metal is 0.01% to 20%, and the mass content of alumina is 80% to 99.99%.

[0019] Furthermore, catalyst B and catalyst C are each independently selected from group VIII metal-modified molecular sieves.

[0020] Further, in catalyst B, the Group VIII metal is Pt and / or Pd; the molecular sieve is at least one of MOR, MFI, FAU, MWW, and EUO, preferably MFI and / or EUO; in catalyst B, the silicon-aluminum molar ratio SiO2 / Al2O3 of the molecular sieve is 20 to 100.

[0021] Furthermore, in the catalyst B, the mass content of Group VIII metal is 0.001% to 1%, based on the mass of catalyst B.

[0022] Further, in the catalyst C, the Group VIII metal is Pt and / or Pd; the molecular sieve is at least one of MOR, MFI, FAU, MWW, and EUO, preferably MFI and / or EUO; in the catalyst C, the silicon-aluminum molar ratio SiO2 / Al2O3 of the molecular sieve is 20 to 100.

[0023] Furthermore, in the catalyst C, the mass content of Group VIII metal is 0.001% to 1% based on the mass of catalyst C.

[0024] Furthermore, the catalyst A is prepared as follows:

[0025] Composite modified alumina was prepared by introducing at least two of Group VIII, Group VIB or Group VIIB metals into a γ-Al2O3 support via an impregnation method.

[0026] Furthermore, the metal precursor used in the impregnation method is a soluble metal salt.

[0027] Furthermore, the impregnation method is preferably equal-volume impregnation.

[0028] Furthermore, after impregnation, the composite modified alumina catalyst can be obtained by drying and calcination. Examples of drying temperatures include 40–250°C, preferably 60–150°C, and examples of drying times include 8–30 hours, preferably 10–20 hours. This drying can be carried out under normal pressure or reduced pressure. The calcination can be carried out in any manner conventionally known in the art; for example, the calcination temperature is generally 300–800°C, preferably 400–650°C, and the calcination time is generally 1–10 hours, preferably 3–6 hours. Additionally, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0029] Furthermore, the preparation method of catalyst B or catalyst C is as follows:

[0030] (a) Take a molecular sieve, place it in a Group VIII metal salt solution, and prepare a modified molecular sieve by ion exchange;

[0031] (b) Take the above modified molecular sieve, add a binder, and prepare the catalyst by molding.

[0032] Furthermore, in the preparation method of catalyst B, the particle size distribution of the molecular sieve in step (a) is 100–1000 nanometers.

[0033] Furthermore, in the preparation method of catalyst C, the particle size distribution of the molecular sieve in step (a) is 10–50 nanometers.

[0034] Furthermore, in the preparation method of catalyst B or catalyst C, the molecular sieve described in step (a) is selected from hydrogen-type or ammonium-type molecular sieves. The molecular sieve is at least one of MOR, MFI, FAU, MWW, and EUO, preferably MFI and / or EUO.

[0035] Furthermore, in the preparation method of catalyst B or catalyst C, the Group VIII metal salt solution mentioned in step (a) is a Group VIII metal nitrate solution or an ammonium nitrate solution. The Group VIII metal is preferably Pt and / or Pd.

[0036] Furthermore, in the preparation method of catalyst B or catalyst C, the operating conditions for ion exchange in step (a) include: a temperature of 20–90°C, preferably 40–80°C; an exchange time of 1–24 hours, preferably 3–5 hours; and a mass ratio of the group VIII metal salt solution to the molecular sieve during ion exchange of 1–10, preferably 3–5.

[0037] Furthermore, in the preparation method of catalyst B or catalyst C, drying and calcination can be performed after ion exchange in step (a). The drying conditions are: a drying temperature of 40–250°C, preferably 60–120°C, and a drying time of 8–30 hours, preferably 10–20 hours. This drying can be carried out under normal pressure or reduced pressure. The calcination can be carried out in any manner conventionally known in the art, with a calcination temperature generally of 300–800°C, preferably 350–500°C, and a calcination time generally of 1–10 hours, preferably 3–6 hours. Additionally, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0038] Furthermore, in the preparation method of catalyst B or catalyst C, the binder mentioned in step (b) is silica sol and / or alumina, preferably silica sol. During the molding process, molding aids can be added, such as guar gum powder, cellulose, cyclodextrin, etc.

[0039] Furthermore, in the preparation method of catalyst B or catalyst C, the catalyst can be obtained by drying and calcining after molding in step (b). The drying conditions are as follows: the drying temperature can be 40–250°C, preferably 60–150°C, and the drying time is 8–30 hours, preferably 10–20 hours. This drying can be carried out under normal pressure or reduced pressure. The calcination can be carried out in any manner conventionally known in the art, with a calcination temperature generally of 300–800°C, preferably 400–550°C, and a calcination time generally of 1–10 hours, preferably 3–6 hours. Additionally, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0040] Furthermore, in the preparation method of catalyst B or catalyst C, the mass content of the binder in the catalyst described in step (b) is 10-90% by mass of oxide, preferably 20-40%.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1. The method provided by this invention concentrates a single reaction unit on C8 + C8 / C9 / C in aromatics 10 C2 in aromatics + While selectively removing the side chain by hydrogenation, xylene isomerization in PX-poor C8 aromatics can also be achieved. This method can be combined with liquid-phase alkyl transfer technology to eliminate the isomerization unit in the existing process, thereby significantly reducing the energy consumption, material consumption and investment of the equipment.

[0043] 2. The method provided by this invention selectively removes C2. + While side-chain substituents and xylene isomerization are involved, it can also facilitate the conversion of downstream disproportionation and alkyl transfer units to liquid-phase reactions or increase the xylene yield of existing disproportionation and alkyl transfer units, eliminating the need for existing isomerization units and helping to restructure aromatic processes. Detailed Implementation

[0044] The technical solution of the present invention will be further illustrated below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0045] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0046] The raw materials used in the embodiments and comparative examples of this invention are commercially available and have an analytical grade (AR) purity.

[0047] In this invention, the formula for calculating the ethyl removal rate is: ((mass of ethyl aromatic hydrocarbons in the raw material - mass of ethyl aromatic hydrocarbons in the product) / mass of ethyl aromatic hydrocarbons in the raw material) × 100%;

[0048] The formula for calculating the propyl removal rate is: ((mass of propyl aromatic hydrocarbons in the feedstock - mass of propyl aromatic hydrocarbons in the product) / mass of propyl aromatic hydrocarbons in the feedstock) × 100%;

[0049] The formula for calculating the aromatic ring loss rate is: ((moles of all aromatics in the feedstock - moles of all aromatics in the product) / moles of all aromatics in the feedstock) × 100%.

[0050] PX equilibrium mass fraction, % = (mass of PX in the liquid product / mass of xylene in the liquid product) × 100%.

[0051] Example 1

[0052] 100g of γ-Al2O3 support was taken, and ammonium molybdate and ammonium perrhenate were used as raw materials. The catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 120℃ for 4 hours, and calcining in air at 550℃ for 3 hours. The mass loading of Mo was 2% and the mass loading of Re was 0.25%.

[0053] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 35) with an average particle size of 200nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.05%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 25% of the catalyst's mass fraction.

[0054] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 25) with an average particle size of 20nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.05%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 25% of the catalyst's mass fraction.

[0055] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 4 wt% and a xylene / C8A ratio of 85 wt%; reformed C8... + The mass ratio of aromatics to PX-depleted C8 aromatics is 80 / 20.

[0056] The reaction temperature was 380℃, the reaction pressure was 1.5 MPa(G), the molar ratio of hydrogen to aromatics was 3 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 50 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 10 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 10 h⁻¹ -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0057] Example 2

[0058] 100g of γ-Al2O3 support was used as raw materials, and Ni and Mo composite modified Al2O3 catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 100℃ for 10 hours, and calcining in air at 500℃ for 5 hours. The mass loading of Ni was 4.5% and the mass loading of Mo was 5.5%.

[0059] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 20) with an average particle size of 900nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.1%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 35% of the catalyst's mass fraction.

[0060] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio 95) with an average particle size of 10nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.1%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 35% of the catalyst's mass fraction.

[0061] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The mass contents of aromatics were 40%, 40%, and 20%, respectively; the C8 aromatics in the PX-lean product came from the C8 aromatics in the isomerization unit feed, with a PX / C8A ratio of 1 wt% and a xylene / C8A ratio of 80 wt%; reformed C8 + The mass ratio of aromatics to PX-depleted C8 aromatics is 90 / 10.

[0062] The reaction temperature was 350℃, the reaction pressure was 1.0 MPa(G), the molar ratio of hydrogen to aromatics was 1.5 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 40 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 10 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 10 h⁻¹ -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0063] Example 3

[0064] 100g of γ-Al2O3 support was used as raw materials, and Pt and Co composite modified Al2O3 catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 120℃ for 10 hours, and calcining in air at 550℃ for 3 hours. The mass loading of Pt was 0.1% and the mass loading of Co was 3.0%.

[0065] 100g of hydrogen-form EU-1 molecular sieve (SiO2 / Al2O3 ratio of 45) with an average particle size of 500nm was placed in 400g of palladium chloride solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pd in ​​the metal-modified molecular sieve was 0.5%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 50% of the catalyst mass fraction.

[0066] 100g of hydrogen-form EU-1 molecular sieve (SiO2 / Al2O3 ratio 45) with an average particle size of 50nm was placed in 400g of palladium chloride solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pd in ​​the metal-modified molecular sieve was 0.5%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 50% of the catalyst mass fraction.

[0067] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 1 wt% and a xylene / C8A ratio of 90 wt%; reformed C8... + The mass ratio of aromatics to PX-poor C8 aromatics is 10 / 90.

[0068] The reaction temperature was 370℃, the reaction pressure was 1.0 MPa(G), the molar ratio of hydrogen to aromatics was 3 / 1, and the aromatic feedstock was C8. +Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 40 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 5 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 5 h⁻¹. -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0069] Example 4

[0070] 100g of γ-Al2O3 support was used as raw materials, and Co and Re were impregnated by equal volume, dried at 100℃ for 6 hours, and calcined in air at 500℃ for 5 hours to prepare a Co and Re composite modified Al2O3 catalyst (catalyst A), wherein the mass loading of Co was 2.5% and the mass loading of Re was 0.20%.

[0071] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 50) with an average particle size of 300nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.03%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 50% of the catalyst mass fraction.

[0072] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio 45) with an average particle size of 25nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.03%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 50% of the catalyst mass fraction.

[0073] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10The mass contents of aromatics were 40%, 40%, and 20%, respectively; the C8 aromatics in the PX-lean C8 were derived from the C8 aromatics in the isomerization unit feed, with a PX / C8A ratio of 1 wt% and a xylene / C8A ratio of 85 wt%; reformed C8 + The mass ratio of aromatics to PX-poor C8 aromatics is 30 / 70.

[0074] The reaction temperature was 340℃, the reaction pressure was 1.0 MPa(G), the molar ratio of hydrogen to aromatics was 2 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 40 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 3 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 3 h⁻¹. -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0075] Example 5

[0076] 100g of γ-Al2O3 support was used as raw materials, and Co and Re were impregnated by equal volume, dried at 100℃ for 6 hours, and calcined in air at 500℃ for 5 hours to prepare a Co and Re composite modified Al2O3 catalyst (catalyst A), wherein the mass loading of Co was 2.5% and the mass loading of Re was 0.20%.

[0077] 100g of hydrogen-form EU-1 molecular sieve (SiO2 / Al2O3 ratio of 35) with an average particle size of 400nm was placed in 400g of palladium chloride solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pd in ​​the metal-modified molecular sieve was 0.7%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 20% of the catalyst's mass fraction.

[0078] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio 55) with an average particle size of 25nm was placed in 400g of palladium chloride solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pd in ​​the metal-modified molecular sieve was 0.7%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 20% of the catalyst mass fraction.

[0079] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 0.5 wt% and a xylene / C8A ratio of 90 wt%; reformed C8... + The mass ratio of aromatics to PX-poor C8 aromatics is 50 / 50.

[0080] The reaction temperature was 385℃, the reaction pressure was 1.0 MPa(G), the molar ratio of hydrogen to aromatics was 5 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 20 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 10 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 10 h⁻¹ -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0081] Comparative Example 1

[0082] 100g of γ-Al2O3 support was taken, and ammonium molybdate and ammonium perrhenate were used as raw materials. The catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 120℃ for 4 hours, and calcining in air at 550℃ for 3 hours. The mass loading of Mo was 2% and the mass loading of Re was 0.25%.

[0083] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 25) with an average particle size of 20nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve with a Pt mass loading of 0.05%. The modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, where the binder (calculated based on Al2O3 mass) accounted for 25% of the catalyst mass.

[0084] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 4 wt% and a xylene / C8A ratio of 85 wt%; reformed C8... + The mass ratio of aromatics to PX-depleted C8 aromatics is 80 / 20.

[0085] The reaction temperature was 380℃, the reaction pressure was 1.5 MPa(G), the molar ratio of hydrogen to aromatics was 3 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 50 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst C is 10 h⁻¹ -1 Catalyst A was placed upstream of catalyst C, and the reaction performance after 24 hours is shown in Table 1.

[0086] Comparative Example 2

[0087] 100g of γ-Al2O3 support was taken, and ammonium molybdate and ammonium perrhenate were used as raw materials. The catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 120℃ for 4 hours, and calcining in air at 550℃ for 3 hours. The mass loading of Mo was 2% and the mass loading of Re was 0.25%.

[0088] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 35) with an average particle size of 200nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve with a Pt mass loading of 0.05%. The modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, where the binder (calculated based on Al2O3 mass) accounted for 25% of the catalyst mass.

[0089] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 4 wt% and a xylene / C8A ratio of 85 wt%; reformed C8... + The mass ratio of aromatics to PX-depleted C8 aromatics is 80 / 20.

[0090] The reaction temperature was 380℃, the reaction pressure was 1.5 MPa(G), the molar ratio of hydrogen to aromatics was 3 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 50 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 10 h⁻¹. -1 Catalyst A was placed upstream of catalyst B, and the reaction performance after 24 hours is shown in Table 1.

[0091] Comparative Example 3

[0092] 100g of γ-Al2O3 support was taken, and ammonium molybdate and ammonium perrhenate were used as raw materials. The catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 120℃ for 4 hours, and calcining in air at 550℃ for 3 hours. The mass loading of Mo was 2% and the mass loading of Re was 0.25%.

[0093] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 35) with an average particle size of 200nm was impregnated with an equal volume of chloroplatinic acid solution, air-dried at room temperature, then dried at 120℃ for 4 hours, and calcined at 550℃ in air for 3 hours to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.05%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10 hours, and calcined at 550℃ in air for 5 hours to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 25% of the catalyst's mass fraction.

[0094] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 25) with an average particle size of 20nm was impregnated with an equal volume of chloroplatinic acid solution, air-dried at room temperature, then dried at 120℃ for 4 hours, and calcined at 550℃ in air for 3 hours to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.05%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10 hours, and calcined at 550℃ in air for 5 hours to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 25% of the catalyst's mass fraction.

[0095] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 4 wt% and a xylene / C8A ratio of 85 wt%; reformed C8... + The mass ratio of aromatics to PX-depleted C8 aromatics is 80 / 20.

[0096] The reaction temperature was 380℃, the reaction pressure was 1.5 MPa(G), the molar ratio of hydrogen to aromatics was 3 / 1, and the aromatic feedstock was C8. + Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 50 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 10 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 10 h⁻¹ -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0097] Comparative Example 4

[0098] 100g of γ-Al2O3 support was taken, and ammonium molybdate and ammonium perrhenate were used as raw materials. The catalyst (catalyst A) was prepared by impregnation with equal volume, drying at 120℃ for 4 hours, and calcining in air at 550℃ for 3 hours. The mass loading of Mo was 2% and the mass loading of Re was 0.25%.

[0099] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 35) with an average particle size of 3 μm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.05%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst B, wherein the amount of binder in catalyst B (calculated based on the mass of Al2O3) accounted for 25% of the catalyst's mass fraction.

[0100] 100g of hydrogen-form ZSM-5 molecular sieve (SiO2 / Al2O3 ratio of 25) with an average particle size of 200nm was placed in 400g of tetraammineplatinum nitrate solution, exchanged at 40℃ for 5h, dried at 120℃ for 4h, and calcined in air at 550℃ for 3h to obtain a metal-modified molecular sieve, wherein the mass loading of Pt in the metal-modified molecular sieve was 0.05%. The above modified molecular sieve was then mixed with alumina binder and guar gum powder, kneaded and shaped, dried at 120℃ for 10h, and calcined in air at 550℃ for 5h to obtain catalyst C, wherein the amount of binder in catalyst C (calculated based on the mass of Al2O3) accounted for 25% of the catalyst's mass fraction.

[0101] The reaction feedstock is reformed C8. + Aromatics and PX-lean C8 aromatics; of which reformed C8 + Aromatic hydrocarbons are derived from C2-containing hydrocarbons produced by catalytic reforming. + C8 / C9 / C of the side chain 10 Aromatic hydrocarbons, including C8 aromatic hydrocarbons, C9 aromatic hydrocarbons and C4 aromatic hydrocarbons. 10 The aromatic hydrocarbon content was 40%, 40%, and 20% respectively; the PX-lean C8 aromatic hydrocarbons came from the C8 aromatic hydrocarbons fed into the isomerization unit, with a PX / C8A ratio of 4 wt% and a xylene / C8A ratio of 85 wt%; reformed C8... + The mass ratio of aromatics to PX-depleted C8 aromatics is 80 / 20.

[0102] The reaction temperature was 380℃, the reaction pressure was 1.5 MPa(G), the molar ratio of hydrogen to aromatics was 3 / 1, and the aromatic feedstock was C8. +Aromatics and PX-lean C8 aromatics, with an aromatic feedstock space velocity of 50 h⁻¹ on catalyst A. -1 The space velocity of the aromatic feedstock on catalyst B is 10 h⁻¹. -1 The space velocity of the aromatic feedstock on catalyst C is 10 h⁻¹ -1 Catalyst A was loaded upstream of catalyst B, and catalyst B was loaded upstream of catalyst C. The reaction performance after 24 hours is shown in Table 1.

[0103] Comparative Example 5

[0104] Same as Example 1, except that only catalysts B and C are used in the reaction, and catalyst A is not used.

[0105] Comparative Example 6

[0106] Same as Example 1, except that catalysts B and C are placed upstream of catalyst A during the reaction.

[0107] Table 1. Evaluation results of each example of the selective hydrogenation-dealkylation coupled xylene isomerization reaction of aromatics.

[0108]

[0109]

Claims

1. A method for selective hydrogenation-dealkylation of aromatics coupled with xylene isomerization, comprising C8... + Aromatic hydrocarbons, PX-depleted C8 aromatic hydrocarbons, and catalysts undergo selective hydrogenation-dealkylation and xylene isomerization reactions. in, The catalyst includes catalyst A, catalyst B, and catalyst C, with catalyst A positioned upstream of catalyst B and catalyst C positioned downstream of catalyst B; wherein, catalyst A is composite modified alumina; and catalyst B and catalyst C are each independently selected from group VIII metal modified molecular sieves.

2. The method according to claim 1, characterized in that, In catalyst B, the molecular sieve modified with group VIII metals has a particle size distribution of 100–1000 nm; in catalyst C, the molecular sieve modified with group VIII metals has a particle size distribution of 10–50 nm.

3. The method according to claim 1, characterized in that, The C8 + Aromatic hydrocarbons are C2-containing hydrocarbons. + C8 of side chain substituents + Aromatic hydrocarbons, preferably containing C2 + C8 / C9 / C of single-ring side chain 10 Aromatic hydrocarbons.

4. The method according to claim 1, characterized in that, The PX-poor C8 aromatic hydrocarbons contain more than 80% xylene by mass and less than 5% PX by mass.

5. The method according to claim 1, characterized in that, The C8 + The mass ratio of aromatic hydrocarbons to PX-depleted C8 aromatic hydrocarbons is (10–90):(90–10).

6. The method according to claim 1, characterized in that, The operating conditions for the reaction include: a reaction temperature of 300–450°C; a reaction pressure of 0.5–5 MPa; and aromatic feedstock consisting of C8 hydrocarbons. + Based on aromatics and PX-lean C8 aromatics, the ratio of the mass hourly space velocity (MHSV) of the aromatic feedstock on catalyst A to that on catalyst B is 5–50; the ratio of the MHSV of the aromatic feedstock on catalyst A to that on catalyst C is 5–50; and the ratio of the MHSV of the aromatic feedstock on catalyst B to that on catalyst C is 5–50. + Aromatic hydrocarbon mass hourly space velocity (MH) is 2–10 h⁻¹ -1 The mass space velocity of the aromatic feedstock on catalyst C is 2–10 h⁻¹. -1 The molar ratio of hydrogen to aromatic feedstock is 1–10 mol / mol.

7. The method according to claim 1, characterized in that, The catalyst A is a composite modified alumina, comprising a modified metal and alumina; And / or, the modified metal in catalyst A includes at least two metals from Group VIII, VIB, and VIIB; wherein the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0-8):(0-8):(0-8); preferably, the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0.01-8):(0.01-8):(0-8); preferably, the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0-8):(0.01-8):(0.01-8); preferably, the mass ratio of the Group VIII metal, Group VIB metal, and Group VIIB metal is (0.01-8):(0-8):(0.01-8); And / or, in catalyst A, the group VIII metal is selected from at least one of Pt, Ni and Co; the group VIB metal is Mo; and the group VIIB transition metal is Re.

8. The method according to claim 1, characterized in that, In catalyst B, the Group VIII metal is Pt and / or Pd; the molecular sieve is at least one of MOR, MFI, FAU, MWW, and EUO, preferably MFI and / or EUO; in catalyst B, the silicon-aluminum molar ratio SiO2 / Al2O3 of the molecular sieve is 20 to 100.

9. The method according to claim 1, characterized in that, In the catalyst C, the Group VIII metal is Pt and / or Pd; the molecular sieve is at least one of MOR, MFI, FAU, MWW, and EUO, preferably MFI and / or EUO; in the catalyst C, the silicon-aluminum molar ratio SiO2 / Al2O3 of the molecular sieve is 20 to 100.

10. The method according to claim 1, characterized in that, In the catalyst A, based on the mass of catalyst A, the mass content of modified metal is 0.01% to 20%, and the mass content of alumina is 80% to 99.99%. And / or, in the catalyst B, the mass content of Group VIII metal is 0.001% to 1% based on the mass of catalyst B; And / or, in the catalyst C, the mass content of Group VIII metal is 0.001% to 1% based on the mass of catalyst C.

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